In what follows, the term empty sliver cans or empty cans will be used, which will include sliver cans that have not yet been completely emptied, but should be taken out of the working position of a spinning station or spindle. A full sliver can is also called a full can. A spinning station, where there is no sliver can for working during the can exchange, is also called an empty station. In contrast to the conventional cylindrical cans, a rectangular sliver can or rectangular can has an essentially rectangular layout or cross section.
In general, the fiber strands to be processed in spinning machines are first drawn and wound on drawing frames or flyers. For example, with the open end method the fiber strands are drawn in three drawing machines placed one after the other and are then filled into empty sliver cans. Today, cans are generally rectangular. The full cans are then transported to the spinning machine. There, the sliver cans are placed into the working position at respective spinning stations. The sliver cans can be exchanged individually, in sections or in entire blocks. In all systems the exchange of a full can for an empty can at a spinning machine can be performed manually or automatically by means of an appropriate device. In a spinning machine, a group of spindles or spinning stations between respectively two supports, which are part of the machine frame, is called a section. The distance between two spinning stations at a section boundary can be greater by a few centimeters than that between two spinning stations within a section.
In the actual open end operation which is common at this time, the filled cans are exchanged for the empty cans coming from the spinning department at the drawing machines, which are positioned ahead of the spinning machine, and are taken manually or by means of automatically controlled transport vehicles to the spinning machine and are there manually or automatically exchanged for empty cans. The empty cans are again returned to the drawing machine, etc.
One problem in many spinning mills lies in that a stacking space for storing or holding the sliver cans in their circuit between the drawing and spinning departments is lacking. Although many cans can stand on the conveying track between each two rows of spinning stations of the spinning machine, if the conveying track is filled with full or empty sliver cans, it is customarily difficult or even impossible to perform a can change (empty cans for full cans) at the spinning station.